With improvements in modular electronic and opto-electronic circuit components, there has developed the need for hardware coupling configurations which afford ease of assembly and minimal signal attenuation across interface points. For example, there are various types of electrode-connectors for coupling printed circuit boards or cards to cabinet or hardware mounting receptacles. Typically, on a printed circuit board, there is formed an intricate pattern of selectively plated or etched conductor which is joined to a considerably physically larger connector electrode arrangement which serves both to electrically connect the card with an interface port in the rack in which it is mounted and to provide actual physical support for the card in its housing. Where these printed circuit boards include electro-optic or opto-electronic components that require the need for optical communication highways such as optical fibers, additional connectors provided exclusively for the optical connections must be provided. Because of the characteristics of optical fibers and their associated optical signalling components, extremely precise coupling between components for minimizing signal loss is required and, in the past, has led to mechanical configurations which are complicated, bulky or hinder the physical handling, namely the insertion and removal, of the printed circuit card or module from the support housing in which it is retained.
FIG. 1 illustrates the general mounting of a printed circuit board 8 that contains a plurality of electronic components 7 that may be joined with one another by way of a selectively etched or plated conductor highway pattern on the surface of the printed circuit card, to a bulkhead type of connector. Printed circuit board 8 may include one or more electro-optic or opto-electronic components 6 electrically coupled to the conductor highway pattern and optically associated with one or more fiber coupling portions 1 each of which contains an individual optical fiber strand or pigtail. The hardware interfacing of the conductor highways on the card to the outside world is usually achieved by a connector 5 physically attached to one end of the card. Such a connector may include a plurality of conductive pins that are electrically joined to the conductor highways on the card and which have a physical configuration such that they couple to an associated plural pin connector mounted to a rack or panel wall 100 in the housing which contains the card 8. The pins of the connector that are mounted in the bulkhead are attached to the wires of the electrical cable which extends exteriorly of the housing. In this fashion, the printed circuit card connector performs a pair of functions: on the one hand, it provides a conductor hardware interface between the components which are connected to the plated conductor highway on the card to the exterior electrical wires. On the other hand, it serves as a mechanical support and attachment for mounting the printed circuit board 8 to the panel 100. Usually, both of these functions are achieved simultaneously simply by inserting the board and its attached connector 5 into a corresponding connector that is mounted on the panel 100. Unfortunately, the coupling of the optical fiber or fibers leading from component 6 to a bulkhead connector 2, particularly in a blind fashion, has not been easily accomplished, since the prior art types of fiber connectors are basically cable-to-cable connectors requiring independent and careful hand manipulation.
In copending patent application Ser. No. 134,225, filed Mar. 26, 1980 entitled "Signal Fiber Connector For Pluggable Card For Module Optical Interconnections", by C. Hillegonds et al, now U.S. Pat. No. 4,406,514, issued Sept. 27, 1983 and assigned to the assignee of the present application, the shortcomings of prior art types of optical fiber connectors are discussed and an improved optical fiber connector for a pluggable card that forms the subject matter of that application is described. With the configuration described in the above copending application, an optical fiber connector configuration includes a connector socket which may be mounted on a printed circuit board or optical module and a connector pin which is attached to a panel by way of which the printed circuit board or module is to be supported. In order to provide automatic guidance of the fibers together, a bracket is mounted on the printed circuit card for holding the connector socket. The bracket is dimensionally positioned relative to the end of the card so that when the card is mounted on the panel through associated hardware, the optical fiber connector and socket will be properly dimensionally located for alignment in fiber coupling. The bracket includes an aperture through which the socket passes and which is of a larger internal diameter than the outside diameter of the socket. The socket is retained in the aperture of the bracket through a compression spring that is preferably seated in a recess in the bracket surrounding the aperture and abuts against a ring held in annular groove in the socket. The spring urges the socket in the direction of the pin to which it is to be joined and cooperates with a section of the socket of wider diameter than the aperture and the ring to hold the socket on the bracket while permitting the male end of the socket to be displaced relative to the axis of the board in the bulkhead mounted pin, thereby assuring a small amount of play between the socket and the axis of the aperture in the bracket, so that a blind fitting of the connector socket and connector pin may be achieved.
While this type of blind rack and panel optical fiber connector provides a certain amount of displacement of the connector socket and the pin relative to each other, so as to assist in the blind mating of the two elements, it has been found that because of the manner in which the socket is mounted in the printed circuit card bracket and is pivotally displaceable by virtue of the aperture in the mounting and a bias spring coupled to the socket and seated in the mounting, the type of displacement that is effectively offered during the blind mating is an angular displacement of the socket, so that the axis of the socket and the axis of the connector pin are not ideally parallel with one another when the two come to be joined together. Since the final objective of any fiber optic connector mounting is to achieve a true face to face abutment of the ends of the fiber strands being mated, the coaxial joining of such fibers is an absolute necessity.